Matteo Cantiello

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Magnetic Fields

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In a star, as in many other astrophysical environments, part of the kinetic and thermal energy of the plasma can be converted into magnetic energy. This is called a “dynamo process”, and requires special configurations of the fluid motions. Once a magnetic field is produced inside a star, it plays an important role for the transport of angular momentum and chemical species. In the stellar evolution code I use, the so-called “Spruit-Tayler”dynamo is included (Spruit, 2002). This dynamo process accounts for the generation of a magnetic field in radiative layers of a star which experience differential rotation. Magnetic fields can also be generated at the boundaries of convective regions. Such dynamo process is believed to give rise to the solar cycle and produce the magnetic fields of sun-spots. Also in the envelope of massive stars a similar dynamo process can occur. Sub-surface convective regions in rotating massive stars could play a role in generating magnetic fields. Emerging at the surface, such magnetic fields could have important observational consequences. For more details of this scenario, check our work on  Sub-surface convection zones in hot massive stars and their observable consequences (Cantiello et al. 2009).

 

I am currently investigating Sub-surface convection in hot massive stars using 3D MHD simulations of convection. For this enterprise I am using the Pencil Code, an MPI, high-order finite-difference code for compressible hydrodynamic flows with magnetic fields.